Crater wear mechanism of wc-co tools at high cutting speeds

Cutting tool wear of polycrystalline cubic boron nitride (PcBN) tools was investigated in oblique turning experiments when machining compacted graphite iron at high cutting speeds, with the intention of elucidating the failure mechanisms of the cutting tools and presenting an analysis of the chip formation process. Dry finish turning experiments were conducted in a CNC lathe at cutting speeds in the range of 500–800m/min, at a feed rate of 0.05mm/rev and depth of cut of 0.2mm. Two different tool end-of-life criteria were used: a maximum flank wear scar size of 0.3mm (flank wear failure criterion) or loss of cutting edge due to rapid crater wear to a point where the cutting tool cannot machine with an acceptable surface finish (surface finish criterion). At high cutting speeds, the cutting tools failed prior to reaching the flank wear failure criterion due to rapid crater wear on the rake face of the cutting tools. Chip analysis, using SEM, revealed shear localized chips, with adiabatic shear bands produced in the primary and secondary shear zones.

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Diffusion Behavior and Wear Mechanism of WC/Co Tools when Machining of Titanium Alloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.279.60 ◽

2018 ◽

Vol 279 ◽

pp. 60-66

Author(s):

Da Shan Bai ◽

Jian Fei Sun ◽

Kai Wang ◽

Wu Yi Chen

Keyword(s):

Diffusion Layer ◽

Wear Mechanism ◽

Cutting Tool ◽

Cutting Tools ◽

Diffusion Behavior ◽

Fine Grain ◽

Diffusion Wear ◽

Material Forming ◽

Wear Modes ◽

Cutting Speeds

In this paper, fine-grain WC/Co tools were utilized in dry turning of the Ti-6Al-4V alloy. The wear modes of the cutting tools at different cutting speeds were analyzed. The diffusion behavior between the cutting tool and the workpiece was studied in detail based on the Auger electron spectroscopy (AES) depth profile technology. The diffusion wear mechanism was revealed. The results showed that the diffusion layer formed at the interface between the cutting tool and the adhering material. The diffusion ability of C was the strongest, followed by W, the weakest was Co in all the elements of the cutting tool. The chemical reactions took place close to the adhering material, forming the reaction layer. As a diffusion barrier, it was possible to limit the elements diffusion from the cutting tool to the adhering material, decrease the changes in the cutting tool composition and damages. The diffusion layer, which was weakened by diffusion, was worn off and taken away by the fast flowing chip during the cutting process, causing the diffusion wear characterized by a smooth crater formation on the tool surface.

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The machinability of Al/B4C composites produced by hot pressing based on reinforcing the element ratio

Science and Engineering of Composite Materials ◽

10.1515/secm-2014-0068 ◽

2016 ◽

Vol 23 (6) ◽

pp. 743-750 ◽

Cited By ~ 2

Author(s):

Ergün Ekici ◽

Mahmut Gülesin

Keyword(s):

Surface Roughness ◽

Wear Mechanism ◽

Cutting Forces ◽

Hot Pressing ◽

Matrix Material ◽

Cutting Tools ◽

Cutting Speed ◽

Reinforcement Ratio ◽

Depth Of Cut ◽

Crater Wear

AbstractIn this study, the effects of the particle reinforcement ratio on cutting forces and surface roughness were investigated when milling particle-reinforced metal matrix composite (MMCp) produced by hot pressing with different cutting tools. Alumix 123 alloy as the matrix material and B4C particles with an average size of 27 μm and 5%, 10% and 15% ratio as reinforcing elements were used for the manufacture of composite materials. The experiments were carried out in dry cutting conditions with four different cutting speeds, constant feed rate and depth of cut. Changes depending on the increased reinforcement ratio in cutting forces and surface roughness values were investigated; the effects of 10% B4C reinforced composite on tool wear were also examined. It was observed that cutting forces increased with the increase in cutting speed and particle ratio with carbide cutting tools, and it was seen that the cutting forces on the cutting tools decreased when cutting speed decreased and the cutting forces increased as the reinforcement ratios increased. In addition, with increasing the cutting speed, the surface roughness of the machined surfaces of composite samples increased with the carbide tools, while the cubic boron nitride (CBN) tools have the opposite effect. While it was seen that flank and crater wear occurred on the cemented carbide cutting tools, abrasive, adhesive and other wear mechanism tools in addition to the main wear mechanism, no remarkable flank and crater wear occurred on CBN cutting tools.

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The Effect of Grain Size and Cobalt Content on the Wear of Ultrafine Cemented Carbide Tools

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.875-877.1344 ◽

2014 ◽

Vol 875-877 ◽

pp. 1344-1351

Author(s):

Jian Bing Cheng ◽

Si Qin Pang ◽

Xi Bin Wang ◽

Chen Guang Lin

Keyword(s):

Grain Size ◽

Tool Wear ◽

Tool Life ◽

Wear Mechanism ◽

Wear Mechanisms ◽

High Strength Steels ◽

Cobalt Content ◽

Cemented Carbide ◽

Cemented Carbide Tools ◽

Cutting Speeds

This work contributes to a better understanding of wear mechanisms of ultrafine cemented carbide cutting tools used in turning operation of superalloy and high strength steels at high cutting speeds. The main objective of this work is to verify the influence of grain size and the cobalt content of ultrafine cemented carbide tools on tool life and tool wear mechanism. The main conclusions are that grain size and the cobalt content of ultrafine cemented carbide tools strongly influence tool life and tool wear involve different mechanisms. The wear mechanisms of different grain size and the cobalt content of ultrafine cemented carbide tools observed on the rake face at these conditions were adhesion and notch, at the end of tool life, adhesion was the main wear mechanism at higher cutting speeds.

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The Genesis of Tool Wear in Machining

Volume 15: Advances in Multidisciplinary Engineering ◽

10.1115/imece2015-52531 ◽

2015 ◽

Author(s):

Trung Nguyen ◽

Kyung-Hee Park ◽

Xin Wang ◽

Jorge Olortegui-Yume ◽

Tim Wong ◽

...

Keyword(s):

Phase Transformation ◽

Tool Wear ◽

Titanium Alloys ◽

Flank Wear ◽

Lamellar Microstructure ◽

Dissolution Mechanism ◽

Low Alloy Steels ◽

Crater Wear ◽

Alloy Steels ◽

Cutting Speeds

This paper presents a series of experimental and theoretical efforts that we have made in unraveling the tool wear mechanisms under steady state conditions in machining for the last few decades. Two primary modes of steady state tool wear considered in this paper are flank and crater wear. We preface this paper by stating that flank wear is explained as abrasive wear due to the hard phases in a work material while crater wear is a combination of abrasive wear and generalized dissolution wear which encompasses both dissolution wear as well as diffusion wear. However, the flank wear was not a function of the abrasive cementite content when turning low alloy steels with pearlitic microstructures. The machined surfaces of these alloys are examined to confirm the phase transformation (ferrite to austenite), which diminishes the effect of cementite content. In particular, the cementite phase present in low alloy steels dissociates and diffuses into the transformed austenitic phase during machining. Dissolution wear is claimed to describe the behavior of crater wear at high cutting speeds. The original dissolution mechanism explains the crater wear in the machining of ferrous materials and nickel alloys at high cutting speeds, but the generalization of the dissolution wear is necessary for titanium alloys. In machining titanium alloys, the original dissolution mechanism did not show a good correlation with experimental results; generally the diffusivity of the slowest diffusing tool constituent in titanium limits the wear rate. The phase transformation from alpha (HCP) to beta (BCC) phases can also take place in machining titanium alloys, which drastically increases the crater wear due to the few orders of magnitude increase in diffusivity. The most puzzling issue is however the presence of the scoring marks even though no hard inclusion is typically present in titanium alloys. This is finally explained by the heterogeneity in the microstructure due to the anisotropic hardness of alpha (HCP) phase (the hardness in c-direction is 50% higher than the hardness in other directions) and the presence of lamellar microstructure (alternating layers of alpha and beta). The lamellar microstructure has not only the in-plane anisotropic hardness but also a greater hardness than other phases. Even though we cannot claim to fully understand the physics behind tool wear, our combined approaches have unveiled some elementary wear mechanisms.

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